/*
 * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
 * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 *
 * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
 *
 *
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 *
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address:
 *
 *  Pearson Education, Inc.
 *  Rights and Contracts Department
 *  75 Arlington Street, Suite 300
 *  Boston, MA 02216
 *  Fax: (617) 848-7047
*/

#include "3ed_query.h"
#include <string>
#include <vector>
#include <map>
#include <set>
#include <iostream>
#include <fstream>
#include <cctype>
#include <cstring>

using std::set;
using std::string;
using std::getline;
using std::map;
using std::vector;
using std::cerr;
using std::cout;
using std::cin;
using std::ifstream;
using std::endl;
using std::pair;
using std::make_pair;
using std::ispunct;
using std::tolower;
using std::strlen;

// read input file: store each line as element in lines_of_text
void TextQuery::store_file(ifstream& is)
{
	string textline;
	while (getline(is, textline))
		lines_of_text.push_back(textline);
}
set<string> TextQuery::exclusion_set = build_exclusion_set();

// \v: vertical tab; \f: formfeed; \r: carriage return are
// treated as whitespace characters along with space, tab and newline
string TextQuery::whitespace_chars(" \t\n\v\r\f");

// finds the whitespace separated words in the input vector
// then puts them in a cannonical form: eliminate suffixes,
// make lowercase etc. Finally, test if its an excluded word or not.
// If not excluded store the word in word_map along with
// its location (line # and character position) info
void TextQuery::build_map()
{
	// process each line from the input vector
	for (line_no line_num = 0;
			line_num != lines_of_text.size();
			++line_num) {
		string textline = lines_of_text[line_num];
		if (textline.empty()) continue; //ignore blank lines

		// make line lower case and remove extraneous punctuation
		strip_caps(textline);
		strip_punct(textline);

		/*
		 * Because we want to keep track of position as well as
		 * line number, we have to process the line a character at a time.
		 * We can't use an istringstream to read the words.
		 * prev_pos will denote first character in each word,
		 * pos will denote whitespace that separates the word from the next
		 * initially pos denotes first non-whitespace at beginning of line
		*/
		str_size pos = skip_whitespace(textline, 0), prev_pos = pos;

		// find each whitespace separated word
		while ((pos = textline.find_first_of(whitespace_chars, pos))
				!= string::npos) {
			// remove suffixes and put the word into the map if apporpriate
			test_insert(textline, prev_pos, pos, line_num);

			// if there's more text to process, increment pos to get next char
			if (pos != textline.size())
				++pos;
			// read and discard adjacent spaces, if any, updating prev_pos too
			pos = prev_pos = skip_whitespace(textline, pos);
		}

		// don't forget last word in the line
		if (pos != prev_pos)  // false if line ends in whitespace
			test_insert(textline, prev_pos, pos, line_num);
	}
}

TextQuery::str_size
TextQuery::skip_whitespace(const string& line, str_size pos)
{
	// ignore adjacent whitespace
	str_size next = line.find_first_not_of(whitespace_chars, pos);
	if (next != string::npos)
		return next;
	else
		return line.size();
}

void TextQuery::test_insert(const string& line, str_size prev_pos,
							str_size pos, line_no line_num)
{
	// make copy of the whitespace delimited word
	string word(line.substr(prev_pos, pos - prev_pos));

	strip_suffixes(word); // last of the cleanup operations

	// if there's anything left after stripping punctuation
	// and it's not an excluded word, add to the map
	// appending line num & char pos to vector for this word
	if (!word.empty() && !exclude_word(word))
		word_map[word].push_back(make_pair(line_num, prev_pos));

	return;
}

void TextQuery::strip_suffixes(string& word)
{
	if (word.size() <= 3)    // too short to have any suffixes
		return;

	if (word[word.size() - 1] == 's')  // only handle plurals so far
		suffix_s(word);

	// additional suffix handling goes here
}

void TextQuery::suffix_s(string& word)
{
	// some words ending in s aren't suffixes, they're part of the word
	static char* ok_endings[] = {"ous", "ius", "ss", "is"};
	size_t sz = sizeof(ok_endings) / sizeof(char*); // how many elements?
	for (size_t i = 0; i != sz; ++i)
		if (chk_ending(word, ok_endings[i]) == 0)
			return;

	// replace common suffixes by their base word ending
	// repl_endings first dimension is the ending we'll remove
	//              second dimension is the new ending we'll insert
	static char* repl_endings[][2] =
	{ {"ies", "y"}, {"ses", "s"}, {"\'s", ""}, {"s", ""} };

	sz = sizeof(repl_endings) / (sizeof(char*) * 2); // two-dimensions
	for (size_t i = 0; i != sz; ++i)
		if (chk_ending(word, repl_endings[i][0]) == 0) {
			size_t sz = strlen(repl_endings[i][0]);
			word.replace(word.size() - sz, sz, repl_endings[i][1]);
			return;
		}
}

// compare end of the word with the ending we're given
int TextQuery::chk_ending(const string& word, const char* ending)
{
	size_t sz = strlen(ending);
	return word.compare(word.size() - sz, sz, ending);
}

void TextQuery::strip_caps(string& line)
{
	// not changing the size of line, so safe to cache the size
	str_size sz = line.size();
	for (str_size pos = 0; pos != sz; ++pos)
		line[pos] = tolower(line[pos]);
}

// except for apostrophe, replace punctuation by a space
// apostrophe is special: it might precede by 's, which is a suffix
void TextQuery::strip_punct(string& line)
{
	for (str_size pos = 0; pos != line.size(); ++pos)
		if (ispunct(line[pos])) {
			if (line[pos] != '\'') line[pos] = ' ';
		}
}

// this function should be changed to let the user specify a
// file of words to ignore, but for now, we'll keep it simple
// and assume a specific file
set<string> TextQuery::build_exclusion_set()
{
	set<string> ret;
	ifstream infile("exclusion_set");
	if (!infile) {
		static string default_excluded_words[] = {
			"the", "and", "but", "that", "then", "are", "been",
			"can", "can't", "cannot", "could", "did", "for",
			"had", "have", "him", "his", "her", "its", "into",
			"were", "which", "when", "with", "would"
		};

		cerr << "warning! unable to open word exclusion file! -- "
			 << "using default set" << endl;

		ret = set<string>(default_excluded_words,
						  default_excluded_words +
						  sizeof(default_excluded_words) / sizeof(string));
	} else {
		string word;
		while (infile >> word) ret.insert(word);
	}
	return ret;
}

bool TextQuery::exclude_word(const string& word)
{
	return (exclusion_set.find(word) != exclusion_set.end());
}

vector<TextQuery::location> TextQuery::run_query(const string& s)
{
	// make local copy so we can clean it up to match words
	// entered in the map; but when communicate back to the
	// user always use their original version
	string sought = s;
	strip_caps(sought);
	strip_punct(sought);
	strip_suffixes(sought);

	// Note: must use find and not subscript the map directly
	// Subscripting a map adds the element if it's not already there
	// We want to know whether the element was there to begin with
	if (word_map.find(sought) == word_map.end())
		return vector<location>();  // not found, return empty location vector
	else
		// fetch list of locations for this word
		return word_map[sought];

}

void TextQuery::display_map()
{
	typedef map< string, vector<location> > map_text;
	map_text::iterator iter = word_map.begin(),
					   iter_end = word_map.end();

	// Note: map iter returns index, value pair
	// so iter->first is the index word,
	// iter->second the vector of its locations

	// for each word in the map
	while (iter != iter_end) {
		cout << "word: " << iter->first << " {";

		vector<location> text_locs = iter->second;
		vector<location>::iterator liter = text_locs.begin(),
								   liter_end = text_locs.end();

		// print all (line,char) locations for this word
		// because this is a debugging routine, don't adjust
		// line/pos numbers.  As normal for programmers, start from 0
		while (liter != liter_end) {
			cout << "(" << liter->first
				 << "," << liter->second << ")";

			if (++liter != liter_end)
				cout << ", ";

		}

		cout << "}\n";  // end list of output this word
		++iter;         // get next word in the map
	}
	cout << endl;  // finished printing entire map
}
